Species: Lontra canadensis

North American River Otter

Species

Mammals

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Terrestrial vertebrates: mammals

Salish Sea-reliant mammals

Encyclopedia of Puget Sound

Articles:

Marine-foraging river otters in the Salish Sea

While not true marine mammals, river otters do use and rely on marine resources. The expansion of their populations since the early 1900s is a true conservation success story. Ecosystem recovery efforts and river otter reintroductions restored otter populations to much of their historic range. River otters often live in small social groups that include mother and offspring or other unrelated adults.

Causes of mortality in marine-foraging river otters

June 08, 2020

North American river otters (Lontra canadensis) inhabit inland freshwater environments; however, from Alaska to California they also occur in coastal marine waters where they forage on a variety of marine fish and invertebrates. Little is known about mortality factors in marine-foraging river otters. Among 30 otter carcasses collected in San Juan County, Washington, analysis indicates that car collisions and gunshots were the most common causes of mortality.

Otter crossing street sign. Photo: Joe Gaydos

Spatial and Temporal Variation in River Otter (Lontra canadensis) Diet and Predation on Rockfish (Genus Sebastes) in the San Juan Islands, Washington

May 24, 2014

A 2014 paper in the journal Aquatic Mammals examines coastal river otter predation on rockfish at three islands in the Salish Sea.

River otter with crab. Photo courtesy of the SeaDoc Society.

Classification

Kingdom

Animalia

Phylum

Craniata

Class

Mammalia

Order

Carnivora

Family

Mustelidae

Genus

Lontra

NatureServe

Source:
ELEMENT_GLOBAL.2.102243

Classification

Other Global Common Names

North American Otter - Northern River Otter - River Otter - loutre de rivière

Informal Taxonomy

Animals, Vertebrates - Mammals - Carnivores

Formal Taxonomy

Animalia - Craniata - Mammalia - Carnivora - Mustelidae - Lontra - Patterns of genetic variation do not concur with current subspecific designations (Serfass et al. (1998), and numerous translocations have crossed subspecies' range boundaries; hence the use of subspecific names is not meaningful in many cases.

Ecology and Life History

Short General Description

A large mustelid (otter).

Habitat Type Description

Freshwater

Migration

true - false - false

Non-migrant

true

Locally Migrant

false

Food Comments

Feeds opportunistically on aquatic animals, particularly fishes (mostly slow-moving, mid-size species), frogs, crayfish, turtles, insects, etc., sometimes birds and small mammals. In coastal waters eats marine species (Bowyer et al. 1995). Commonly preys on nesting seabirds in some areas (e.g., Alaska islands). See Toweill and Tabor 1982 for many further details.

Reproduction Comments

Implantation is delayed 8 months or more. Gestation, including delayed implantation, lasts 9-12 months. In many areas, births peak in late winter-early spring; parturition dates may not be closely synchronized within a given population. Litter size is 1-6 (average 2-3); 1 litter per year. Young may first enter water at about 7 weeks, are weaned at about 3 months, stay with mother for about a year. Male may rejoin family after young leave den. Females breed for the first time at 2 years. Males become sexually mature at 2 years, but may not breed successfully until 5-7 years old. Females evidently breed in alternate years in some areas (e.g., Alabama, Georgia), every year in Oregon (see Toweill and Tabor 1982).

Ecology Comments

Home range typically is linear; 20-30 miles for a pair or male; less for females with young (Jackson 1961). May hunt over as much as 80-100 km of stream during the course of one year. In coastal Alaska, summer home range size averaged around 20 km of shoreline in males, 10 km in females, with ranges twice as large in oiled areas (Bowyer et al. 1995). <br><br>Population density of one per 2.2 miles has been recorded (Baker 1983). Density was estimated at one otter per 86 ha of coastal marsh in Louisiana (Shirley et al. 1988). In Idaho, density was one family group and 1-3 subadults or nonbreeding adults per 15 km of waterway, plus one breeding adult male for each 20-30 km of waterway (see Toweill and Tabor 1982). Density in coastal areas of the Gulf of Alaska was 0.30-0.85 otters/km of shoreline (Testa et al. 1994, Bowyer et al. 1995).

Length

131

Weight

13600

Conservation Status

NatureServe Global Status Rank

Global Status Last Reviewed

1996-11-18

Global Status Last Changed

1996-11-18

Distribution

Conservation Status Map

Global Range

FG - 20,000-2,500,000 square km (about 8000-1,000,000 square miles) - FG - Throughout most of North America north of Mexico, except the extreme southwestern U.S. Extirpated from large areas of the interior U.S. following European colonization. Has been reintroduced in some parts of the range (e.g., Colorado, Virginia).

Global Range Code

Global Range Description

20,000-2,500,000 square km (about 8000-1,000,000 square miles)

ELEMENT_GLOBAL.2.102243